Technical Field
The disclosure relates to a two stage quick-release structure, and particularly to a two stage quick-release structure for foldable bicycle.
Related Art
Foldable bicycles were invented for convenient storage and carrying. Commonly, a quick-release structure is assembled on the bicycle frame. Therefore, when the bicycle is not in use, the user can release the quick-release structure of the foldable bicycle quickly to fold and store the foldable bicycle; while when the foldable bicycle is in use, the user can assemble the foldable bicycle quickly without using additional tools.
Different kinds of quick-release structures are commercially available. Typically, two combining blocks are applied as the quick-release structure; one ends of the two combining blocks are connected via a pivoting shaft with the unconnected ends of the two combining blocks respectively having buckling members. The combining means of the buckling members can be different. As shown in FIG. 1, the buckling hook is applied as the buckling members. A first combining block 91 and a second combining block 92 are respectively soldered on the front bicycle frame body and the rear bicycle frame body, and the first combining block 91 is rotatable relative to the second combining block 92 via a pivoting shaft 93. The first combining block 91 has an engaging portion 94, and the second combining block 92 has a buckling handle 95 pivotally disposed thereon. The buckling handle 95 includes a buckling hook 951 and a protruding member 952. When the user assembles the foldable bicycle, firstly, the front bicycle frame body is rotated relative to the rear bicycle frame body via the pivoting shaft 93 so that the first combining block 91 is correspondingly combined with the second combining block 92. Then, the buckling hook 951 of the buckling handle 95 is hooked with the engaging portion 94 of the first combining block 91 and fastened with the bicycle frame on where the second combining block 92 is soldered (here, the second combining block 92 is soldered on the rear bicycle frame body). Thereafter, a safety fastener 96 on the rear bicycle frame body is rotated to buckle with the protruding member 952 of the buckling handle 95 so as to prevent from the buckling handle 95 loosing from the engaging portion 94 during bicycling. However, such combining means applies only one buckling hook to combine the bicycle frames, thus contributing to the issues of unsecure combining and ease of detaching during bicycling or after long term use.
Additionally, the first combining block 91 and the second combining block 92 are combined with the bicycle frames by means of soldering mostly, which will leave apparent welding marks; furthermore, since widths of the first and second combining blocks 91, 92 are larger than the diameter of the bicycle frame, the appearance of the foldable bicycle is not attractive.